(1) Field of the Invention
The present invention relates to an improved manually operated device for lowering a person along the exterior face of a building wall and in particular, the present device is particularly useful under emergency conditions to provide a means for escape from a building.
(2) Prior Art
There have been many types of devices proposed for lowering a person to the ground along an exterior face of a building wall. One of the problems with such devices is controlling the speed of descent. If the user descends too quickly, he may be injured by contact against the building wall, or the ground. Controlling the speed of descent is even more critical under emergency escape conditions, where the user may be inexperienced or partially incapacitated, and under emotional stress. Under such circumstances it is preferred that the device be of simple construction, foolproof, and easily operated.
U.S. Pat. No. 275,608 to Drake, patented on Apr. 10, 1883, discloses a fire escape device having a drum mounted upon an axle. The device includes a pair of snap hooks at each end of the drum and a rope wound about the drum with a loop secured at one end thereof. A braking device is included which comprises a slide pin which is in frictional engagement with one of the side walls of the drum and is activated by a pivoted lever. When the lever is manually pivoted, one end thereof contacts the frictional pin causing it to engage the side wall of the drum.
The Drake device is not designed to be employed with a rail vertically attached to the exterior face of a building.
U.S. Pat. No. 2,647,675 to Bernett, issued on Aug. 4, 1953, discloses a gasoline powered car designed to travel along the vertical face of a building in order to rescue persons from the building during emergency conditions. The car travels along an I-beam secured to the vertical face of a building. Along one flange of the I-beam includes a rack having a plurality of teeth designed to mesh with a rotating gear directly coupled to the car. The vehicle includes a braking system comprising a pair of brake shoes securely mounted to the frame of the vehicle. The brake shoes have semi-circular linings and are designed to frictionally engage a brake drum which is mechanically coupled to the gear which engages the rack. In this manner the vehicle may be stopped at any point along the rack.
U.S. Pat. No. 4,406,349 to Vilchek issued on Sept. 27, 1983 discloses an emergency escape apparatus which includes a gear track mounted vertically on the exterior surface of a building. A carriage is provided with guide rollers which engage a guide track oriented adjacent and parallel to the gear track. A gear wheel is rotatably mounted on the carriage and is maintained in positive engagement with the gear track by the guide rollers. The carriage includes automatic brakes which serve to limit the maximum downward velocity of the carriage. A boatswain's chair is attached to the carriage to transport one or more individuals down the vertical face of the building. The brake system includes a centrifugal brake and a cam brake. The cam brake includes a plurality of brake pads mounted in semi-circular fashion around a brake drum to which force is applied by a plurality of semi-circular brake bands.
The above devices are unsafe or too complicated and do not accurately control the speed of descent, particularly under emergency conditions where the user may be inexperienced or partially incapacitated, and under emotional stress. Accordingly, there exists a need for a device for manually lowering a person from a building along the exterior face of the building.